The present invention broadly relates to an apparatus for the processing of fluid or fluent materials, and, more specifically, relates to a new and improved construction of a thin film treatment apparatus, especially a thin film evaporator for the treatment of flowable or liqueform materials.
Prior art thin film treatment apparatus possess a heated or cooled rotationally symmetrical housing, for instance in the form of a conical or cylindrical housing, within which there is arranged a rotor driven by a motor. The rotor is equipped with scraper or distributor elements which uniformly distribute the liquid infed from above and onto the inner wall of the housing. These scraper or distributor elements simultaneously ensure that the solids which have solidified from the liquid and have deposited at the housing wall will be removed.
The rotors can have scraper elements or the like of the most different constructions. Thus, for instance, there are known to the art scraper elements which are mounted at the rotor and are pressed by the action of centrifugal force against the inner wall of the housing. In this way there is achieved a uniform distribution of the liquid and a scraping of the solids or solid materials. What is disadvantageous with this state-of-the-art construction is that the scraper elements experience a pronounced wear, so that the dried material is contaminated. Furthermore, the solids which are to be separated can accumulate in the bearings of the scraper elements at the rotor, so that the scraper elements no longer can be moved or only with extreme difficulty. Consequently, the scraper elements no longer can be directed towards the housing wall by the effect of the centrifugal forces which act during operation of the thin film treatment apparatus.
Furthermore, there is also known to the art a thin film treatment apparatus having a rotor containing wire brushes. These wire brushes comprise wires extending in radial direction. With this construction there is achieved a lesser wear and the scraper elements are elastically resilient, however also with this construction there is a tendency for the solids to accumulate at the surface of the rotor, specially in the wire brushes. When this happens the mobility of the scraper elements is reduced or prevented and there is required a frequent cleaning of the rotor in order to avoid operational disturbances.